Chemical Compounds & Number of Bonds 2. In the drawing on the ...
Chemical Compounds & Number of Bonds 1. Take a look at the two diagrams of an HF molecule drawn below. H is hydrogen. F is fluorine. HF is a poisonous gas. What’s different about the drawings? HF
HF
2. In the drawing on the right, what does the line connecting the H atom to the F atom represent?
3. Both of these are perfectly acceptable ways of drawing an HF molecule. In “real life” however, there isn’t actually a little line that connects the H atom to F atom. Why would it be useful to make the drawings like that even if it isn’t true in real life?
4. For the rest of this handout, we’re going to show the lines (bonds) so that it’s easier to see what atoms are bonded to. Take a look at the following two diagrams of a water molecule. It can be shown (with a battery and wires) that water is a compound particle with the formula H2O. H2O
H2O
One of those diagrams looks like water molecules you’ve seen before. One of them looks different. Which one is correct?
Read this: In a molecule, it’s not just which atoms are bonded that matters. It also matters how the atoms are bonded -- what order and what arrangement they have. Over many, many years, lots of careful observations and experiments, like the one that we did with water and the wires and battery, led chemists to begin to make conclusions about how different types of atoms bond. They noticed patterns in how many bonds different atoms made. The rest of this worksheet is going to quickly guide you through the conclusions that chemists made. 5. Summarize what you just read.
6. The following molecules represent real chemicals and how they bond. H2O
H2
HF
NaOH
Na2O
NH3
7. Look at the molecules drawn above. What do you notice about the bond(s) that hydrogen makes?
8. Are there any exceptions? Or does hydrogen always make 1 bond?
9. Complete the table with information about the number of bonds made by other types of atoms based on the drawings above: Element Calcium Chlorine Hydrogen Lithium Nitrogen Oxygen Potassium
Symbol Ca Cl H Li N O K
Bonds 2 1 ________ 1 ________ ________ 1
10. When lithium makes a compound with oxygen, the molecules look like this:
and have the formula Li2O. Using the table of bond information, explain why.
Element Calcium Chlorine Hydrogen Lithium Nitrogen Oxygen Potassium
11. Using the table of bond information make drawings for the molecules that are made when these elements combine to form compounds. a. Lithium and nitrogen Drawing:
Formula:
b. potassium and chlorine Drawing:
Formula:
c. hydrogen and calcium Drawing:
Formula:
d. potassium and oxygen Drawing:
Formula:
e. calcium and oxygen (Hint: atoms can bond to each other twice!) Drawing: Formula:
Symbol Ca Cl H Li N O K
Bonds 2 1 1 1 3 2 1
Bonds and the Periodic Table 1. The periodic table is organized (partly) by how many bonds each type of atom makes! To figure out the pattern, write the number of bonds each element makes next to the symbol on the periodic table (only main group elements shown) below. Element Symbol Bonds Calcium Ca 2 Chlorine Cl 1 Hydrogen H 1 Lithium Li 1 Nitrogen N 3 Oxygen O 2 Potassium K 1 Phosphorous P 3 Silicon Si 4 Sulfur S 2 Xenon Xe 0
2. What do you notice about the number of bonds made by elements in the same column (group)?
3. What do you notice about the number of bonds made by elements in the same row (period)?
4. Based on your answers to 2 and 3 predict the number of bonds each element would make. Sodium (Na):
Bromine (Br):
Carbon (C):
Aluminum (Al):
5. Read this: Why are the transition elements not shown in the periodic table? That part of the periodic table is weird and the number of bonds a transition element makes is much harder to predict than main group elements.
HF
2. In the drawing on the right, what does the line connecting the H atom to the F atom represent?
3. Both of these are perfectly acceptable ways of drawing an HF molecule. In “real life” however, there isn’t actually a little line that connects the H atom to F atom. Why would it be useful to make the drawings like that even if it isn’t true in real life?
4. For the rest of this handout, we’re going to show the lines (bonds) so that it’s easier to see what atoms are bonded to. Take a look at the following two diagrams of a water molecule. It can be shown (with a battery and wires) that water is a compound particle with the formula H2O. H2O
H2O
One of those diagrams looks like water molecules you’ve seen before. One of them looks different. Which one is correct?
Read this: In a molecule, it’s not just which atoms are bonded that matters. It also matters how the atoms are bonded -- what order and what arrangement they have. Over many, many years, lots of careful observations and experiments, like the one that we did with water and the wires and battery, led chemists to begin to make conclusions about how different types of atoms bond. They noticed patterns in how many bonds different atoms made. The rest of this worksheet is going to quickly guide you through the conclusions that chemists made. 5. Summarize what you just read.
6. The following molecules represent real chemicals and how they bond. H2O
H2
HF
NaOH
Na2O
NH3
7. Look at the molecules drawn above. What do you notice about the bond(s) that hydrogen makes?
8. Are there any exceptions? Or does hydrogen always make 1 bond?
9. Complete the table with information about the number of bonds made by other types of atoms based on the drawings above: Element Calcium Chlorine Hydrogen Lithium Nitrogen Oxygen Potassium
Symbol Ca Cl H Li N O K
Bonds 2 1 ________ 1 ________ ________ 1
10. When lithium makes a compound with oxygen, the molecules look like this:
and have the formula Li2O. Using the table of bond information, explain why.
Element Calcium Chlorine Hydrogen Lithium Nitrogen Oxygen Potassium
11. Using the table of bond information make drawings for the molecules that are made when these elements combine to form compounds. a. Lithium and nitrogen Drawing:
Formula:
b. potassium and chlorine Drawing:
Formula:
c. hydrogen and calcium Drawing:
Formula:
d. potassium and oxygen Drawing:
Formula:
e. calcium and oxygen (Hint: atoms can bond to each other twice!) Drawing: Formula:
Symbol Ca Cl H Li N O K
Bonds 2 1 1 1 3 2 1
Bonds and the Periodic Table 1. The periodic table is organized (partly) by how many bonds each type of atom makes! To figure out the pattern, write the number of bonds each element makes next to the symbol on the periodic table (only main group elements shown) below. Element Symbol Bonds Calcium Ca 2 Chlorine Cl 1 Hydrogen H 1 Lithium Li 1 Nitrogen N 3 Oxygen O 2 Potassium K 1 Phosphorous P 3 Silicon Si 4 Sulfur S 2 Xenon Xe 0
2. What do you notice about the number of bonds made by elements in the same column (group)?
3. What do you notice about the number of bonds made by elements in the same row (period)?
4. Based on your answers to 2 and 3 predict the number of bonds each element would make. Sodium (Na):
Bromine (Br):
Carbon (C):
Aluminum (Al):
5. Read this: Why are the transition elements not shown in the periodic table? That part of the periodic table is weird and the number of bonds a transition element makes is much harder to predict than main group elements.
